Definitions for "Cutoff Frequency"
The frequency above which a filter will start attenuating signals present at its input. Abbreviated Fc. In most synths it refers to the low pass filter but can be others like a high pass filter.
The upper or lower frequency beyond which no appreciable energy is transmitted.
A point where higher frequency cycles will not pass through a filter (e.g., a 10-day SMA will eliminate cycles of 20 days or less).
Keywords:  hertz, phase, square, wave
Hertz phase square wave
Keywords:  slope
Cutoff slope